Average Thickness Control for Blown Film

Average Thickness Control for Blown Film

A less expensive and more accurate option than gravimetric control.

Controlling average thickness is very valuable to almost all blown film producers. If they have tight control of thickness, they can make sure they don’t give away extra polymer or get hit with yield penalties. Just 1% better control can equate to millions of dollars per year for some large producers.

Many film lines currently use gravimetric systems which do a good job of accurately outputting a given weight of material. The problem is that producers are really concerned with the thickness of film they are producing. Therefore, a complex calculation and additional sensors are required to get to the average thickness value. This can all lead to error in the final thickness versus the calculation. The user also has to know his product’s density, and this can be especially difficult with multi-layer films. I often here of operators entering an incorrect value, causing serious issues.

In other cases, a producer may not have automated average thickness control, and operators are doing their best to stay on target manually.

SolveTech has a unique solution to this problem, the BF200, that does not require you to know the density of the material or even have a gravimetric system. Our proprietary capacitance technology can hold calibration, and this is unlike any of the on-the-bubble single-sided capacitance gauging systems. The on-the-bubble systems are simply variability gauges and are fed average thickness information via the gravimetric control.

SolveTech’s BF200 is precise to better than 0.01 mils and can deliver an average thickness reading at this precision or better. This has been proven in the field time and time again. The user does not have to know the density of the material, they simply calibrate using a material sample of known thickness. The calibration is also fairly insensitive to changes in density or formulation.

The gauge provides the additional benefit of monitoring the profile around the bubble, and all of this information can be output via OPC server. The system is easily retrofitted to existing lines and provides an excellent value to cost ratio.